In the ear auxiliary microphone system for behind the ear hearing prosthetic

ABSTRACT

An In The Ear (ITE) microphone improves the acoustic response of a Behind The Ear (BTE) Implantable Cochlear Stimulation (ICS) system during telephone use. An acoustic seal provided by holding a telephone earpiece against the ear provides improved coupling of low frequency (up to about 1 KHz) sound waves, sufficient to overcome losses due to the near field acoustic characteristics common to telephones. In an exemplary embodiment, the ITE microphone is connected to a removable ear hook of the BTE ICS system by a short bendable stalk.

The present application is a Divisional of U.S. application Ser. No.10/823,879, filed Apr. 14, 2004, to be issued as U.S. Pat. No. 7,167,572on Jan. 23, 2007; which application is a Divisional of U.S. applicationSer. No. 09/927,130, filed Aug. 10, 2001, issued as U.S. Pat. No.6,775,389; and is related to U.S. application Ser. No. 10/731,049, filedDec. 9, 2003, issued as U.S. Pat. No. 7,003,876; which applications andpatents are incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

The present invention relates to hearing devices for aiding the hearingimpaired and the profoundly deaf, and more particularly to an In The Ear(ITE) auxiliary microphone connected to a Behind The Ear (BTE) speechprocessor through a removable ear hook. The microphone of the presentinvention is especially useful for a user conversing over a telephone.

Implantable Cochlear Stimulation (ICS) systems are known in the art.Such systems are used to help the profoundly deaf (those whose middleand/or outer ear is dysfunctional, but whose auditory nerve remainsintact) to hear. The sensation of hearing is achieved by directlyexciting the auditory nerve with controlled impulses of electricalcurrent, which impulses are generated as a function of perceived audiosounds. The audio sounds are picked up by a microphone carriedexternally (not implanted) by the deaf person and converted toelectrical signals. The electrical signals, in turn, are processed andconditioned by a Wearable Signal Receiver and Processor (WP) in anappropriate manner, e.g., converted to a sequence of pulses of varyingwidth and/or amplitude, and then transmitted to an implanted receivercircuit of the ICS system. The implanted receiver circuit generateselectrical current as a function of the processed signal it receivesfrom the WP (which in turn is based on the audio sounds picked up by theexternal microphone). The implanted receiver circuit is connected to animplantable electrode array that has been implanted into the cochlea ofthe inner ear. The electrical current generated by the implantedreceiver circuit is applied to individual electrode pairs of theelectrode array. It is this electrical current which directly stimulatesthe auditory nerve and provides the user with the sensation of hearing.

While known ICS systems have succeeded in providing hearing to the deaf,ICS systems also have the disadvantage of appearing unsightly. ICSsystems include an external headpiece, positioned on the side of theuser's head, and require an external cable running from the externalheadpiece to the WP. The WP is typically worn or carried by the user ona belt or in a pocket. While the WP is not too large, it is likewise notextremely small, and hence also represents an inconvenience for theuser. The cable which connects the WP with the headpiece is particularlya source of irritation and self-consciousness for the user.

The above-described aesthetic considerations and inconvenience of anexternal wire are addressed by U.S. Pat. No. 5,824,022, issued Oct. 20,1998, for “Cochlear Stimulation System Employing Behind-The-Ear (BTE)Speech Processor With Remote Control.” The '022 patent teaches a smallsingle external device that performs the functions of both the WP andthe headpiece. The external device is positioned behind the ear tominimize its visibility, and requires no cabling to additionalcomponents. The '022 patent is incorporated herein by reference.

While the BTE device taught by the '022 patent resolves the issues ofaesthetics and inconvenience, the placement of the microphone in the BTEdevice case results in poor microphone performance when using atelephone. The near field acoustic characteristics of known telephones,and the absence of a seal between the telephone earpiece and themicrophone in the BTE case, degrades the coupling of low frequencyinformation up to about 1 KHz. Further, known ICS systems and hearingaids use a telecoil residing near the earpiece of a telephone handset todetect the magnetic field produced by the speaker in the handset,however, low magnetic field phones and cell phones using piezotransducers, do not couple well with telecoils.

Therefore, there is a need to improve the performance of known ICSsystems when the user is conversing over a telephone.

SUMMARY OF THE INVENTION

The present invention addresses the above and other needs by providingan In The Ear (ITE) microphone that improves the acoustic response of aBehind The Ear (BTE) Implantable Cochlear Stimulation (ICS) systemduring telephone use. An acoustic seal provided by holding a telephoneearpiece against the outer ear provides improved coupling of lowfrequency (up to about 1 KHz) sound waves, sufficient to overcome lossesdue to the near field acoustic characteristics resulting from thetelephone microphone cooperation. In a preferred embodiment, the ITEmicrophone is connected to a removable ear hook of the BTE ICS system bya short bendable stalk.

In accordance with one aspect of the invention, there is provided an ITEmicrophone for a BTE ICS system, which microphone is placed within theconcha of the ear. When a telephone handset is held against the ear, thephone seals against the outer ear, creating a chamber wherein themicrophone resides. Sealing the microphone within such chamber resultsin improved frequency fidelity due to the sealing in of the soundpressure. Such sealing also reduces the amount of outside noise thatreaches the microphone. Advantageously, the BTE ICS system does notrequire any earmolding to provide adequate sealing. Further, thepositioning of the microphone within the ear improves hearing by usingthe natural acoustics of the ear.

It is a further feature of the invention to provide a BTE ICS systemthat works equally well with low magnetic field phones and cell phonesusing piezo transducers which do not couple well to a telecoil. The ITEmicrophone relies entirely on the acoustic signal transmitted by thespeaker in the telephone handset, which speaker is designed to achievethe acoustic performance objectives of the unaided hearing population.The performance of the BTE ICS system using the ITE microphone istherefore unaffected by the type of speaker (or sound transducer) usedin the telephone handset.

It is an additional feature of the present invention, that whenexercised in conjunction with an ICS system, there is no acousticfeedback from a microphone to affect performance. Conventional hearingaids use a speaker in the user's ear to broadcast an amplified acousticsignal to the user. If an ITE microphone was used in the same ear, theresult would be severe acoustic feedback. The present invention isapplied to ICS systems, wherein the output of the ICS system iselectrical stimulation of the cochlea, not an acoustic signal.

It is a further additional feature that use of the ITE microphone doesnot result in chafing to the skin of the ear. The ITE microphone of thepresent invention includes a bendable stalk, which stalk retains a shapeonce the stalk is bent into that shape. The stalk may thus be bent toavoid rubbing against the skin of the ear, and the resulting chafing ofthe skin.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will be more apparent from the following more particulardescription thereof, presented in conjunction with the followingdrawings wherein:

FIG. 1A depicts a prior art BTE device and earhook;

FIG. 1B depicts the prior art BTE device and earhook placed upon the earof a user;

FIG. 1C shows the prior art BTE device and earhook with the earhookdetached from the BTE device;

FIG. 2 shows the BTE device with the In The Ear (ITE) microphoneattached;

FIG. 3 depicts the BTE device with ITE microphone attached placed uponthe ear of a user;

FIG. 4 shows a front view of the ITE microphone and earhook;

FIG. 4A shows a cross-sectional view of the ITE microphone and earhooktaken along line 4A-4A of FIG. 4; and

FIG. 5 shows a cross-sectional view of a preferred embodiment of the ITEmicrophone and earhook taken along line 4A-4A of FIG. 4.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best mode presently contemplated forcarrying out the invention. This description is not to be taken in alimiting sense, but is made merely for the purpose of describing thegeneral principles of the invention. The scope of the invention shouldbe determined with reference to the claims.

The In The Ear (ITE) microphone of the present invention improves theacoustic response of a Behind The Ear (BTE) Implantable CochlearStimulation (ICS) system during telephone use. As shown in FIG. 1A, whencombined (or connected together), a prior art earhook 12 and BTE device10 of an ICS system resemble a common BTE hearing aid. The earhook 12 isarched and hooks in front of the ear. The BTE device 10 continues thearch to the rear of the ear and is positioned behind the ear. A batterycompartment 14 is removably attached to the bottom of the BTE device 10.Various batteries of different sizes may be interchangeably attached tothe BTE device 10 depending upon the needs of a user. A more detaileddescription of a BTE device may be found in U.S. Pat. No. 5,824,022,previously incorporated herein by reference. In known BTE devices 10, aBTE microphone is positioned in the case of the BTE device 10 behind amicrophone port 16. The earhook 12 typically defines a recesscooperating with the port 16 to facilitate the communication of soundwaves with the BTE microphone. The BTE device 10 with the earhook 12attached, is shown residing on an ear 18 in FIG. 1B.

Turning to FIG. 1C, a coaxial connector 20 is shown attached to the BTEdevice 10. Such co-axial connector 20 is disclosed in currently pendingU.S. patent application Ser. No. 09/785,629 filed Feb. 16, 2001 for“Connector System for BTE Hearing Devices.” The coaxial connector 20serves as both an attaching fixture for the standard earhook 12 andspecial earhooks (i.e., provides a mechanical connection), and as anelectrical connector for auxiliary devices (i.e., provides an electricalconnection between the BTE electronics circuits and other electronicdevices or sensors included within, or attached to, an earhook).Advantageously, the dual use feature of the coaxial connector 20eliminates the need to provide a separate connector for connecting(electrically or mechanically) auxiliary devices to the BTE device 10.The '629 application teaches the construction and use of the co-axialconnector to mechanically and electrically connect a special earhook toa BTE device 10. The '629 application also discloses several specialearhooks intended to add features to the BTE ICS device. The '629application does not however contemplate a special earhook whichprovides an ITE microphone. The '629 application is herein incorporatedby reference.

An ITE microphone earhook 22 is shown attached to the BTE device 10 inFIG. 2. The ITE microphone earhook 22 comprises a second earhook 24, amicrophone assembly 26, and a stalk 28 mechanically and electricallyconnecting the microphone assembly 26 to the earhook 24. The microphoneassembly 26 includes a soundport 30 defined at a distal end of themicrophone assembly 26. The stalk 28 preferably is bendable andpreferably retains a position into which the stalk 28 is bent. In apreferred embodiment, the ITE microphone earhook 22 is attached to theBTE device 10 using the coaxial connector 20 of the '629 patent,however, those skilled in the art will recognize that a variety ofapparatus and methods of attaching an ITE microphone to a BTE device areavailable. Further, the ITE microphone 25 need only be electricallyconnected 21 to the speech processor 23 of an ICS system, including aBTE system, and may include other means to secure the ITE microphone(e.g., any means that might be used to secure a common earphone mayprove suitable to secure the ITE microphone) in place. These other meansfor connecting the ITE microphone to the BTE device are intended to comewithin the scope of the present invention.

The ITE microphone earhook 22 and BTE device 10 are shown residing onthe ear of a user in FIG. 3. The microphone assembly 26 preferablyresides behind the tragus and directed towards the concha of the ear,with the soundport 30 facing downward and somewhat rearward. Some usersmay vary location of the microphone assembly 26, and these variationsare intended to come within the scope of the present invention. Thesoundport 30 receives sound waves and is open to the volume between theearpiece 31 of a communications handset, such as a telephone handset,and the ear of a user.

A front view of the ITE microphone earhook 22 is shown in FIG. 4, and across-sectional view of the ITE microphone earhook 22 taken along line4A-4A of FIG. 4 is shown in FIG. 4A. A mating connector 36 is shownresiding in the earhook 24. Such mating connector may be any connectorsuitable to electrically and mechanically connect the earhook 24 to theBTE device 10. Preferably, the mating connector 36 is the matingconnector described in the '629 application. Those skilled in the artwill recognize that other connectors may be used to connect the earhook24 to the BTE device 10, including separate connectors for mechanicaland electrical connecting. A microphone 34 resides in the microphoneassembly 26, and is connected by at least one conductor 32 to the matingconnector 36. While the conductor 32 preferably is electricallyconnected to the mating connector 36, in other embodiments the conductor32 may be electrically connected to an electrical connector independentof the mating connector 36, or may exit the ITE microphone earhook 22and electrically connect to a connector on the exterior of the BTEdevice 10.

A cross-sectional view of a preferred embodiment of the ITE microphoneearhook 22, taken along line 4A-4A of FIG. 4, is shown in FIG. 5. Themicrophone 34 resides in a sleeve 52, wherein the sleeve 52 ispreferably made from brass. A filter 48 seals the microphone 34 from theenvironment, while letting sound pass to the microphone 34. In apreferred embodiment, the microphone 34 comprises an FG Seriesmicrophone manufactured by Knowles Electronics Inc. in Itasca, Ill., andpreferably an FG3329. The FG3329 microphone is operated in a two wiremode using a bias setting resistor 42. The at least one conductor 32comprises three conductors 32 a, 32 b, and 32 c attached at a distal endof the stalk 28 to three terminals on the FG3329 microphone. One of thethree conductors 32 a, 32 b, and 32 c is electrically connected to acontact 46 in the center of the mating connector 36, and two of thethree conductors 32 a, 32 b, and 32 c are connected to the bias settingresistor 42, and to the body of the mating connector 36. The threeconductors 32 a, 32 b, and 32 c are carried in a single cable 44, andthe cable 44 is wound with two stiffening members 38, which stiffeningmembers 38 are preferably made from wire, more preferably from zinc orcopper. The stiffening members 38 enable the stalk 28 to be bent into adesired shape, and to retain the shape. The wound combination of thecable 44 and the stiffening members 38 is covered by shrink tubing 54.The stiffening members 38 allow the stalk 28 to be bent into variousshapes to better fit a user, and to retain such shapes. The stiffeningmembers 38 are connected to the sleeve 52. The stiffening members 38provide the stalk 28 with the ability to be bent and to retain theposition into which the stalk 28 is bent. The volume 50 behind themicrophone 34 is filled with potting compound to prevent the conductors32 a, 32 b, and 32 c from flexing and detaching from the microphone 34when the stalk 28 is adjusted. The entire assembly including themicrophone 34, sleeve 52, and conductors 32 a, 32 b, and 32 c, iscovered by a boot 56, preferably molded from an elastomer.

A method of constructing the ITE microphone earhook 22 is as follows.The conductors 32 a, 32 b, and 32 c are soldered to terminals on themicrophone 34 to form a first sub-assembly. The stiffening members 38are soldered to the sleeve 52 to form a second sub-assembly. The firstsub-assembly is inserted into the second sub-assembly, wherein theconductors 32 a, 32 b, and 32 c are guided into the end of the sleeve 52opposite the stiffening members 38, until the end of the microphone 34opposite the conductors 32 a, 32 b, and 32 c is flush with the end ofthe sleeve 52 opposite the stiffening members 38. The resulting cavityin the sleeve 52 containing the conductors 32 a, 32 b, and 32 c isfilled with potting compound and allowed to cure. (This creates a solidstructure of the microphone, cable, sleeve and flexible members so thatany bending in the stalk will not be transferred to the solder joints ofthe conductors 32 a, 32 b, and 32 c that would weaken and eventuallyfail the connection.) After curing of the potting compound, thestiffening members 38 and the cable 44 are twisted together as a groupto about 3 turns per inch. Shrink tubing 54 is applied over thestiffening members 38 and the cable 44, up to the base of the sleeve 52,to form the ITE microphone stalk 28. The filter 48 is attached to theend of the sleeve 52 opposite the stalk 28 to protect the microphone 34from moisture. The microphone 34 and stalk 28 assembly is then inserted,stalk 28 first, through the large opening of the microphone boot 56. Themicrophone boot 56 will stretch over the sleeve 52 and encapsulate theentire microphone assembly. The curved tube 58 is soldered to the matingconnector 36, and the stalk 28 is inserted into the curved tube 58. Theproper length of the stalk 28 is determined, and the two stiffeningmembers 38 are then soldered to the inside diameter of the matingconnector 36 for a mechanical connection. The conductors 32 a, 32 b, and32 c are then soldered to the appropriate terminals of the matingconnector 36 and the resistor 42. After soldering is completed, thevolume around the soldered connections is potted with epoxy to cover theconnections and the resistor 42 to protect them from damage during theover mold process of the ear hook. The mating connector 36, curved tube58, and adjacent end of the stalk 28 are over molded with a medicalgrade PVC to form the ear hook to complete the ITE microphone earhook22.

An ITE microphone for use with BTE ICS systems has been described. TheITE microphone resides within a sealed chamber formed by the telephone,or other communications device, handset earpiece, and the ear. As aresult of sealing in the sound waves, the low frequency near fieldacoustic degradation otherwise experienced by the user are substantiallymitigated, and a significant improvement in the quality of the soundperceived by the ICS system user results. The ITE microphone performsequally well with traditional telephones and with low magnetic fieldphones and cell phones using piezo transducers which do not couple wellwith telecoils.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations could be made thereto by those skilled in the art withoutdeparting from the scope of the invention set forth in the claims.

1. A Behind The Ear (BTE) Implantable Cochlear Stimulation (ICS) system,comprising: a BTE unit of the ICS system, wherein the BTE unit includesa speech processor; an earhook configured to be removably attachable tothe BTE unit; a microphone assembly, wherein the microphone assemblyincludes a microphone having three terminals, and wherein the microphoneis configured to be electrically connected to the speech processor usinga first conductor, a second conductor, and a third conductor, whereinthe first conductor is connected to a mating connector and wherein thesecond and third conductors are connected to a bias setting resistor;and a bendable, formable stalk having a first end attached to theearhook and a second end directed towards the inside of an ear; andwherein the microphone assembly is attached to the second end of thestalk.
 2. The system of claim 1 wherein the microphone assembly furthercomprises a filter at a distal end of the microphone assembly, whereinthe filter seals the microphone from the environment.
 3. The system ofclaim 1 wherein the stalk is formed of shrink tubing.
 4. The system ofclaim 1 wherein the microphone assembly further includes a sleevewherein the microphone resides.
 5. The system of claim 4, furthercomprising: at least one stiffening wire member having a first wire endand a second wire end, wherein the first wire end terminates proximatethe mating connector and the second wire end is attached to the sleeve;and a cable, wherein the conductors reside within the cable; and whereinthe at least one stiffening wire member and the cable are wound to formthe bendable, formable stalk.
 6. The system of claim 1 wherein themicrophone is positioned in the ear so that when an earpiece of acommunications handset is held to the ear, a soundport is open to thevolume between the earpiece and the ear.
 7. The system of claim 6wherein the communications handset is a telephone handset.
 8. The systemof claim 1 wherein the stalk is adapted to retain a bend once bent,whereby a user may adjust the position of the microphone by bending thestalk.
 9. The system of claim 1 wherein the mating connector is acoaxial connector configured to be attached to the BTE unit.
 10. ABehind The Ear (BTE) Implantable Cochlear Stimulation (ICS) system,comprising: a BTE unit of the ICS system, wherein the BTE unit includesa speech processor; an earhook configured to be removably attachable tothe BTE unit, wherein the earhook includes a mating connector; amicrophone configured to be electrically connected to the speechprocessor wherein the microphone includes a soundport in one end andmultiple terminal on the other; and a bendable, formable stalk having afirst end attached to the earhook and a second end directed towards theinside of an ear; and wherein the microphone is attached to the secondend of the stalk.
 11. The system of claim 10, wherein the terminal endof the microphone includes a first conductor, a second conductor, and athird conductor, wherein the first conductor is connected to the matingconnector and wherein the second and third conductors are connected to abias setting resistor.
 12. The system of claim 10, wherein themicrophone further comprises a filter at a distal end of the microphone,wherein the filter seals the microphone from the environment.
 13. Thesystem of claim 10, wherein the stalk is formed of shrink tubing. 14.The system of claim 10, wherein the microphone further includes a sleevewherein the microphone resides.
 15. The system of claim 14, furthercomprising: at least one stiffening wire member having a first wire endand a second wire end, wherein the first wire end terminates proximatethe mating connector and the second wire end is attached to the sleeve;and a cable, wherein the conductors reside within the cable; and whereinthe at least one stiffening wire member and the cable are wound to formthe bendable, formable stalk.
 16. The system of claim 10 wherein themicrophone is positioned in the ear so that when an earpiece of acommunications handset is held to the ear, the soundport is open to thevolume between the earpiece and the ear.
 17. The system of claim 16wherein the communications handset is a telephone handset.
 18. Thesystem of claim 10 wherein the stalk is adapted to retain a bend oncebent, whereby a user may adjust the position of the microphone bybending the stalk.
 19. The system of claim 10 wherein the matingconnector is a coaxial connector configured to be attached to the BTEunit.